Hydraulic circuit for holding and pushing cylinders of tunneling machine



v. J. SCARAVILLI ET Al. 3, HYDRAULIC CIRCUIT FOR HOLDING AND PUSHINGCYLINDERS OF TUNNELING MACHINE Dec. 31, 1968 l of 5 Sheet Original FiledApril 11,

Dec. 31, 1968 v. J. SCARAVILLI ETAL 3,419,311

HYDRAULIC CIR CUIT FOR HOLDING AND PUSHING CYLINDERS OF TUNNELINGMACHINE Jriginal Filed April 11, 1966 Sheet 2 of5 INVENTORS were 1504241040, (cl/424:5 .z O'L/S/O Dec. 31, 1968 v. J. SCARAVILLI ET LHYDRAULIC CIRCUIT FOR HOLDING AND PUSHING CYLINDERS 0F TUNNELING MACHINEOriginal Filed April 11, 1966 Sheet o y L M w 0 4 a w w wunl NJ em 4 J54 e O a 5 a w 4, W Y 4 5 2 Dec. 31, 1968 v. J sc l ET AL 3,419,311

HYDRAULIC CIRCUIT FOR HOLDING AND PUSHING CYLINDERS OF TUNNELING MACHINEOriginal Filed April 11, 1966 Sheet 4 of 5 1968 v. J. scum/Lu m13,419,311

HYDRAULIC CIRCUIT FOR HOLDING AND PUSHINC CYLINDERS 0F TUNNELING MACHINEOriginal Filed April 11, 1966 Sheet 5 of INVENTORS W670? J SCAF/V l/M/J.f (HA/P166 .1. 054 4:70

United Smtes Patent M 3,419,311 HYDRAULIC CIRCUIT FOR HOLDING AND PUSH-ING CYLINDERS OF TUNNELING MACHINE Victor J. Scaravilli, Beechwood, andCharles J. Delisio, Lyndhurst, Ohio, assignors to S & M Constructors,Inc., Bedford Heights, Ohio, a corporation of Ohio Original applicationApr. 11, 1966, Ser. No. 541,673, now Patent No. 3,383,138, dated May 14,1968. Divided and this application Dec. 4, 1967, Ser. No. 712,311

2 Claims. (Cl. 299-31) ABSTRACT OF THE DISCLOSURE A tunneling machinehaving a support frame anchorable in a tunnel bore by four independentlyhydraulically actuated support feet at each of two axially spaced zoneswhich provide the only anchoring of the support frame in the tunnel andby individual movement selectively position the axis of the supportframe with respect to the axis of the tunnel. An elongated movable frameis carried on the support frame by two axially spaced sets ofarticulated torque arm assemblies which position the movable frameradially with respect to the support frame and transmit torque betweenthe movable frame and the support frame. A cutter head is mounted on thefront end of the movable frame by a large thrust bearing and a cutterhead support plate is insulated from the remainder of the movable frameby a layer of elastomeric material to absorb and dampen shocktransmission between the cutter and the bearing. The cutter head isrotatably driven by an elongated shaft which extends from the cutterhead axially through the movable frame to a drive motor assembly at therear end of the machine. At its rear end the movable frame hasselectively operable support feet which allow the movable frame to besupported by its own support feet and the cutter head, while the supportframe is advanced along the tunnel by the reversible push cylindersinterconnecting the support frame and the movable frame to provide thenecessary thrust to the cutter head.

This application is a division of our co-pending application, Ser. No.541,673, filed Apr. 11, 1966, and now Patent No. 3,383,138.

This invention relates generally to tunneling machines and moreparticularly to tunneling machines having a rotary boring or cuttinghead for boring passages through hard rock and minerals.

The digging of a tunnel through soft material such as clay and soft rockor only partially consolidated materials has long been done by machineshaving a rotary cutting head having cutters which scrape and dig away atthe material which is then collected and removed rearwardly from thetunnel. However, when such machines are used against harder materials,and particularly very hard igneous and metamorphic rocks, such scrapingtype cutters cannot be used and it is necessary to go to percussive typeroller cutters which chip away small fragments from the mass of rock byimpact. The use of such cutters has long been known for drilling Wellsand other relatively small diameter holes, but efforts to adapt suchcutters to larger machines for use in drilling tunnels has met withconsiderable ditficulty because of the necessary forces involved and theshock loads encountered. As a result, such cutters have been so slow andhave encountered so many breakdown problems that it has been necessaryto still use blasting type tunneling methods in such material. The useof blasting methods has been recognized as undesirable not only becauseof the problems of danger and expense, but also the fact that the tunnelwalls tend to be irregular in shape and excessive fracturing of thewalls re- 3,419,311 Patented Dec. 31, 1968 quires considerable cementingand support to prevent possible collapse after the tunnel is dug. Thus,while the desirability of a tunneling machine for hard rock has longbeen recognized, heretofore none of the machines have been suflicientlypractical to operate with a high enough degree of reliability and at afast enough cutting rate to make them competitive with other tunnelingmethods.

Therefore, it is a principal object of this invention to provide a noveltunneling machine utilizing a fixed anchored carriage and an axiallymovable rotary cutting head adapted to out even the hardest rock at ahigh rate of speed.

It is a further object of this invention to provide a novel tunnelingmachine as set forth in the preceding object which has an improvedarrangement for anchoring the supporting frame in the previously dugtunnel which does not depend on the weight of the machine.

It is another object of this invention to provide a novel tunnelingmachine as set forth in the preceding objects which has an improveddriving mechanism for the cutter head to allow efidcient application andutilization of sufficient power to produce a high cutting speed.

It is another object of this invention to provide a novel tunnelingmachine as set forth in the preceding objects having a novel arrangementfor transmitting the reaction and shock torques from the movable cutterhead support to the supporting frame and for mounting and positioningthe movable frame with respect to the fixed supporting frame.

It is another object of this invention to provide in a rotary cutterhead a novel shock absorbing mounting to reduce the transmiszion ofshock loads between the cutter supporting plate and the rest of themachine.

It is a further object of this invention to provide a new and improvedtunneling machine which provides improved steering, easy accessibilityof the machine while cutting, as well as high reliability and ease ofrepair or replacement of the component parts of the machine.

Briefly, the foregoing and further and additional objects and advantagesof this tunneling machine are accomplished by providing a fixedsupporting frame anchored in the tunnel wall by two axially spaced setsof projecting arms, each set of which has four arms equidistantly spacedand actuated by hydraulic cylinders to position the frame without regardto the weight of the machine, A movable frame is carried centrallywithin the supporting frame by sets of torque arms at each end whichboth support the moving frame and transmit the reaction torque from themoving frame to the supporting frame. A cutter head is mounted inbearings at the front end of the moving frame and carries a cutter platehaving a number of roller cutters mounted thereon. The cutter plate ismounted to the rotating shaft by means of a shock absorbing andinsulating mounting of elastomeric material arranged to allow a limitedamount of relative movement to absorb shock loads. A drive shaft extendsthe length of the moving frame to project beyond the rear end of thesupporting frame where the shaft is driven by a motor assembly. The longlength of the drive shaft gives it a limited amount of torsionalmovement which absorbs the shock loads and prevents them from reachingthe drive motors. Hydraulic cylinders acting between the supportingframe and the cutter head apply the force directly to the bearingsupporting the cutter head to cause the moving frame to move relative tothe supporting frame. After the moving frame has moved through its fullrange of movement, a jack is lowered at the rear end to support themoving frame by the jack and the cutter head to allow the supportingframe to have the arms retracted and move forward to the next positionwhere the supporting frame is again anchored to allow the cuttingmovement to continue.

Further objects and advantages of this invention will become apparent tothose skilled in the art upon a more complete understanding of theinvention, the preferred embodiment of which is described in thefollowing detailed description and shown in the accompanying drawings inwhich:

FIGURE 1 is a rear quarter perspective of a tunneling machine recordingto the present invention;

FIGURE 2 is an elevational view partially in section with parts brokenaway of the machine shown in FIG- URE 1;

FIGURE 3 is a rear end elevational view of the machine;

FIGURE 4 is a cross-sectional View taken on line 44 of FIGURE 2;

FIGURE 5 is a sectional view with parts broken away for clarity taken online 55 of FIGURE 2;

FIGURE 6 is an enlarged fragmentary cross-sectional view showing detailsof the mounting of the cutter support late; p FIGURE 7 is a fragmentarycross-sectional view of the hinge pin of the torque arms;

FIGURE 8 is a fragmentary cross-sectional view showing anotherembodiment of the torque arm hinge pin;

FIGURE 9 is a fragmentary elevational cross-sectional view showing analternative mounting for the front support for the moving frame; and

FIGURE 10 is a schematic diagram of the hydraulic circuit of themachine.

Referring now to the figures in greater detail, the general arrangementof the machine is best shown in FIG- URES 1 and 2. The machine has asupport frame indicated generally at 10 which is braced against thetunnel walls to position the machine in proper alignment and absorb thetorque and thrust forces produced by the cutting action. The supportframe 10 has a longitudinal tubular center section 12 which terminatesat each end in a front support section 13 and a rear support section 14.For ease of assembly, the tubular section 12 may be formed of twochannel-like members joined together by bolts along a center line as at11.

Each of the support sections 13 and 14 carry four radially extendingholding feet, spaced equidistantly in planar alignment, which arepressed against the tunnel walls by hydraulic cylinders. For thispurpose, each of the support sections, which, except as hereinafterdescribed are identical, have four tubular guide collars 16 secured totheir outer surfaces to guide the radially movable holding or supportfeet 17 which terminate at their outer ends in arcuate pads 18 which maybe provided with projecting studs 19 to prevent slippage along thetunnel wall. The pads 18 may be either rigidly or pivotally attached tothe feet 17, depending on whether it is necessary to cut a tunnel havinga short radius of curvature. Within each of the guide collars 16 is ahydraulic holding cylinder 21 having a rod 22 connected at 23 to thefoot pad to force the pad tightly into engagement with the tunnel wall.It will be seen that since the only contact between the support frameassembly 10 and the wall is at the eight pads 18, four on each of thetwo sections, the longitudinal axis of the tubular section 12 may thusbe guided and aligned for steering purposes by adjusting the relativeradial extension of the pads by the holding cylinders. Thus, the axismay be shifted by at one of the support sections extending one of thepads while retracting the diametrically opposite pad to shift the entireassembly. Since the support frame is not mounted on rails or wheels,this allows the axis of the support frame to be shifted without regardfor the weight of the machine or the downward position.

Within the tubular section 12 is positioned a movable carriage frametube 26 which floats freely within the tubular section 12 and extendsbeyond the front and rear support sections 13 and 14. At its front end,the carriage frame tube 26 carries an enlarged cutter head housing 28having an annular axially extending outer wall 29 which supports theouter race of a bearing 31. The hearing 31 is preferably of the highcapacity double row tapered roller type adapted to absorb both radialloads and thrust loads in either direction. The split inner race ofbearing 31 is secured on the outer surface of a cutter head hub 33 tojournal the latter for rotation with respect to the housing 28. Aretainer plate 34 positions one side of the split inner race of bearing31 whose other race is held by a bearing spacer 36 positioned betweenthe bearing and a radial flange 41 on the hub 33.

The bearing 31 is sealed to prevent the entry of water and dirt at twoplaces. An annular seal support plate 37 (see also FIGURE 6) is securedby screws 38 to the front edge of the annular wall 29 and carries a seal39 adapted to make sliding sealing contact against the outer surface ofthe front bearing spacer 36. In addition, a seal support collar 43 issecured on the outer peripheral sun face of the support plate 37 byscrews 44 and is provided with a seal-receiving groove 45. Within groove45 are inner and outer seals 46 and 47, held in place by a retainerplate 48, and arranged to make sealing contact with a smooth sealingsurface 42 on the outer periphery of the radial flange 41. Both of theseals 46 and 47 have a flexible outwardly extending sealing lip whichallows material to pass outward from within the sealed area but preventsthe entrance of foreign matter. To enhance the effectiveness of thisseal under operating conditions, grease fittings 51, a plurality ofwhich are arranged around the periphery of the support collar 43, are anranged to allow intermittent injection of a lubricating grease or thelike into the space between the seals 46 and 47 so as to wash out anyforeign matter which might have entered past the outer seal 47 whilestill retained by the inner seal 46. The use of this intermittentinjection of grease not only lubricates the seal but continually cleansit and insures that any rock chips wedged beneath the outer seal will beremoved before more than a minimal amount of foreign matter can get pastthe outer seal.

The radial flange 41 on the cutter head hub 33 serves as the support forthe cutter head assembly. This assembly includes a cutter support plateextending parallel to the flange 41 and to which is secured the cutterplate 56 by suitable means such as bolts 57. The cutter plate 56 isshown as having three arms 58 (see FIGURE 1) on which are mounted theroller cutter assemblies 59. These cutter assemblies may be of any ofthe roller cutter type which have a rolling surface having projectionsadapted to impact and locally crush the rock so it breaks loose. Thecutters 59 are spaced around the cutter plate 56 both in the center andalong the arms 58 in a manner to provide a relatively uniform thrustloading on the plate centered on the axis of the bearing 31, andarranged in a staggered manner so that all portions of the rock facebeing cut are engaged by at least two cutters. Since the construction ofthe roller cutter assemblies 59 forms no part of this invention, theyhave not been shown or described in detail. It is also recognized thatother types of cutters such as kerf cutters and the like may be employedif the machine is used in softer material more adapted to cutters ofthat type.

In order to remove the rock chips produced by the cutting action, scoops52 are located on the rear faces of the cutter plate arms 58 andcooperate with a moldboard 54 supported on the cutter head housing asshown in FIGURE 1. The material picked up by the scoops 52 can then bedischarged when they reach the uppermost position onto a suitable beltconveyor (not shown) which may be mounted on top of the machine betweenthe upper holding legs to convey the material rearwardly of the machine.

An important feature of this invention is the mounting of the cuttersupport plate 55 to the radial flange 41 on the cutter head hub 33. Aparticular problem is encountered When local variations in the hardnessof the rock produce a change of the torsional and thrust loadsencountered by the cutters which results in a shock or impact loadingbeing transferred to the cutter plate 56 and cutter support plate 55.Such high impact loads can be very damaging to the bearings and otherstructure because they may be of high intensity. Therefore, a shockabsorbing resilient mounting is provided between the flange 41 and thesupport plate 55 in the form of a layer of elastomeric materialinterspacing the flange 41 and the support plate 55.

The details of this arrangement are shown generally in FIGURE 2 and ingreater detail in FIGURE 6. The cutter support plate 55 is spaced fromthe flange 41 by a layer of elastomeric material 66 which is bonded toboth of these members and secures them together. The radial flange 41 isprovided with a plurality of openings 53 extending therethrough betweenits front and rear faces. Preferably, these openings 53 are spacedequidistantly around the face on the same radius and may be as high astwenty or thirty in number. A bolt or cap screw 61 is secured to thecutter support plate 55 and extends rearwardly through the opening 53within which it is generally centered. A cylindrical sleeve 62 surroundsthe bolt 61 to abut at its front end against the support plate 55 and atits rear end against a flanged collar 64 which in turn abuts against thehead of the bolt 61. A conical spring washer or Belleville spring 65 iscompressed by the collar 64 against the rear face of the flange 41 underan initial preload. The elastomeric material 66 fills the space betweenthe sleeve 62 and the Openings 53 and extends rearwardly as far as therear face 67 of the flange 41.

Although a number of materials may be used as the elastomeric material,it has been found that a suitable and preferred material is a castpolyurethane polymer because of the ability of this material to beeasily cast in place as a liquid resin and bond to the metal it is incontact with while providing a high degree of hardness and tensilestrength with the ability to absorb impact loads. One such material isNovitane S, grade CU83 sold by the B. F. Goodrich Company, IndustrialProducts Division. The assembly may be easily made by mounting the hub33 and cutter support plate 55 in a fixture which seals the outer edgeswhile spacing them apart by the desired distance. The bolt 61 and sleeve62 are assembled in place and a plain washer substituted for the flangedcollar 64 and spring washer 65, and the bolt 61 is then tightened sothat the washer seals off the rear face of the opening 53. The liquidpolymer is then poured into the space to completely fill it in anannular zone around the central opening 68 in the cutter support plate55 as well as in the openings 53. After the polymer has hardened, theassembly is then mounted on the machine after the plain washers havebeen replaced by the flanged collar 64 and spring washer 65.

When the machine is in operation, the compression loads from the cutterswill be transmitted to the cutter plate 56 and then to the cuttersupport plate 55, so that the elastomeric material 66 will be incompression to absorbshocks and prevent them from being transmitted tothe radial flange 41. Because the elastomeric material fills the spacebetween the sleeve 62 and the opening 53, the torque applied to thecutters is also transmitted through the elastomeric material so thattransient loads in both thrust and torque encountered by the cutters arenot transmitted to the cutter head hub 33. The function of the springwasher 65 is normally to resiliently absorb rebound loads in the eventthat the loading on the cutter plate 56 is uneven to resist tilting andforces which might tend to break the bond between the elastomericmaterial and either the flange 41 or the cutter support plate 55.

The cutter head hub 33 and the cutter head assembly secured to it isrotatably driven by means of a drive shaft 70 within the carriage frametube 26 and extending axially therealong back to the drive motorassembly which is located rearward of the rear support section 14. Thedrive shaft is non-rotatably secured to the cutter head hub 33 by meansof keys 71 and is clamped in place against axial movement by a taperedcollar 72 secured in place within the hub by suitable means such asscrews 74. The drive shaft 70 extends lengthwise through the carriageframe tube 26 to the rear end Where it is totatably journaled by abearing 76 mounted within a bearing housing 77 secured to the rear endof the frame tube. The housing 77 also serves to support a cup-shapeddrive housing 79 whose rear face is closed off by a plate 81. Within thehousing 79 a drive hub 82 is nonrotatably carried by the rear end of theshaft 70 to which it is secured by means of keys 83 and screws 84. Thehub 82 carries a drive Wheel 86 to the rear face of which is secured aninternal ring gear 87. A plurality of electric motors 89, shown as beingthree in number, are mounted by being secured to the rear plate 81 andconnected together at their other ends by a bracket 91. Each of themotors 89 is positioned on the plate 81 so that a pinion gear 92 on itsshaft is in driving engagement with the ring gear 87. This provides fora suitable gear reduction for the motors, so that the ring gear throughthe drive wheel 86 and hub 82 can rotate the drive shaft 70 to rotatethe cutter head hub 33 and the cutter head assembly. Because of the longlength of the drive shaft 70 and the extremely high torques and loadsinvolved, it allows a certain amount of torsional damping of anytorsional shock loads encountered by the cutter head assembly.

All of the moving carriage including the carriage frame tube 26, thecutter head assembly at the front end and the drive assembly at the rearend is supported on the support frame 10 to allow limited axial movementtherealong by a pair of front and rear torque arm assemblies 94 and 95.These assemblies are identical and suspend the carriage frame withoutthe requirement for any guide rollers or rails while also absorbing therotating torque and side thrust loads imposed on the cutter head. Thereaction torque to the driving force of the cutter head is transmittedalong the drive shaft 70 to the rear drive assembly and therefore istaken up primarily by the rear torque arm assembly 95. The front torquearm assembly 94 thus basically serves to support the cutter head housing28 and to absorb any lateral loads which may result from uneven cuttingor a change in cutting direction.

Turning to the torque arm assemblies in greater detail, each assemblyincludes four articulated torque arm units arranged equidistantly incircular fashion so that they may operate together and insure positiveaxial alignment between the carriage frame tube 26 and the tubularsupport section 12. Each torque arm unit consists of,

as seen in the front assembly, an inner arm 97 which is pivotallymounted on a pair of spaced yoke-shaped brackets 99 carried on the frontface of the front support section 13. Each of the brackets 99 carries apivot pin 100 on which are journaled a pair of ears 102 secured to thetorque arm 97. Suitable thrust washers 103 are positioned between thesides of the ears 102 and the brackets 99 to transmit the forces fromthe torque arm to the brackets while permitting free rotation of thetorque arm about the pivot pins 100. The torque arm has a generallytriangular shaped center section 104 tapering from the ears 102 to aprojecting car 105 which is positioned slightly off center from the axisof the inner torque arm.

The torque arm unit includes an outer torque arm 107 which may beidentical in shape with the inner torque arm 97. The outer torque arm107 is pivotally journaled on a pair of spaced, yoke-shaped brackets 109supporting pivot pins 110 and being secured on the rear face of thecutter head housing 28. The outer torque arm 107 likewise has an offsetear 112 which is pivotally connected to the ear 105 on the inner torquearm 97 as shown in 7 greater detail in FIGURE 7. The ears 105 and 112are bored to receive bushings 114 and 115, respectively, through whichpasses a pivot pin 116 which is secured against axial movement at itsends by lock nuts 118 and 119.

It will be understood that as shown, the cutter head rotates in aclockwise direction as seen from the rear so that it advances with whatamounts to a right-handed helix. Thus, the reaction torque of the cutterhead housing 28 and carriage frame tube 26 is in the opposite directionso that the reaction torque must be transmitted from the outer torquearm 107 to the inner torque arm 97. However, any sudden decrease intorque, after all wind-up has been taken out of the mechanism will tendto produce a relative movement in the opposite direction for whichprovision must be made. Accordingly, the nut 118 next to car 105 isprovided with a thrust Washer 121 between it and the side of the ear. Apair of thrust washers 123 are positioned between the ears 105 and 112and non-rotatably secured to the respective ears by locating pins 125. ABelleville spring 127 is mounted between the other nut 119 and the car112. This allows the reaction forces to be taken up by the thrustwashers 123, but in the event of any rebound action in the oppositedirection, deflection of the spring washer 127 and the bearing providedby thrust washer 121 allow the shock to be taken up without exertingexcessively high tensile loads on the pivot pin 116.

As shown in FIGURE 2 when the cutter head assembly is in the forwardposition, the rear torque arm assembly 95 is in the folded positionwhile the front torque arm assembly 94 is in the extended position.While, as previously stated, most of the reaction torque is taken up bythe rear torque arm assemblies, some of the torque may also betransmitted through the front torque arm assemblies. However, theseassemblies are the same except that they are reversed end for endbecause the torque is being transmitted from the brackets 129 secured tothe drive housing 79 to the outer arm 130 and from there to the innerarm 131 which is pivotally mounted on brackets 132 carried on the rearface of the rear support section 14.

In order to provide the necessary axial force for the cutters againstthe rock face being cut, a plurality of push cylinders are providedbetween the support frame and the cutter head housing 28. As shown inFIGURES 4 and 5, there are four push cylinders arranged equidistantlyabout the front support section 13 between the guide collars 16. Eachpush cylinder 135 is connected by means of a pin 136 to a bracket 137mounted at the rear face of the front support section 13 and tubularsection 12. The cylinder 135 extends forward parallel to the axis of themachine between adjacent guide collars 16 and has a piston rod 139connected by means of a pin 140 to a bracket 141 mounted on the rearface of the cutter head housing 28. By the use of the four cylinders ofequal size and operating at the same pressure, the axial forces on thecutter head assembly will be balanced to minimize any bending loads onthe carriage frame tube and drive shaft.

After the cutter head assembly has advanced the full stroke of the pushcylinders 135 to the position generally shown in FIGURE 2, it isnecessary to re-position the supporting frame in the tunnel at a moreforward position so that the next cutting cycle may begin. While this isdone by retracting all of the holding cylinders 21 and then reversingthe push cylinders 135, it is necessary to support the carriage frameduring this movement so that the support frame will be free from contactwith the walls. At its front end, the cutter head assembly, having anouter diameter equal to that of the tunnel bore, is supported on thecutter plate arms 58. In order to support the drive mechanism at therear end of the carriage frame, a pair of feet actuated by liftcylinders are provided for support at such times. As seen in FIGURES 1through 3, a pair of lift cylinders 142 are located adjacent the drivemotors 89 and at their upper end are connected to pivot pins 143 carriedon the rear plate 81 of the drive housing 79. The lift cylinders 142have downwardly extending push rods 145 which are connected to pads 146by pivot pins 147. The pads 146 are curved to make contact with thecurved tunnel walls and if desired, may have gripping studs on them. Thepivot pin 147 also serves to connect the outer end of positioning arms149 which at their inner end are connected by a pivot pin 151 to abracket 152 secured to the bottom of the drive housing 79. The linkageformed by the arms 149 and lift cylinders 142 insures positivepositioning of the pads 146 when the lift cylinders are actuated tosupport the drive housing and the rear end of the carriage.

Thus, when the cutter head assembly reaches the end of the stroke, thelift cylinders 142 are actuated to bring the pads 146 into contact withthe tunnel walls to support the drive housing 79 in the position it isin. After this has been done, the holding cylinders 21 can be retractedto bring the foot pads 18 out of engagement with the tunnel wall. Then,the push cylinders 135 are reversed so that the support frame 10 movesforward until the push cyl inders are fully retracted. In that position,the holding cylinders are again expanded to bring the foot pads 18 intocontact with the tunnel wall so that the support frame 10 is tightlypositioned in the tunnel. After this has been done, the lift cylinders142 are used to retract the pads 146 and the push cylinders and drivemechanism can then be reactivated to start a new cutting cycle.

The hydraulic circuit of the machine is shown in detail in the schematiccircuit diagram of FIGURE 10. The circuit includes an electric motor 155adapted to drive a positive displacement hydraulic pump 156 which takesfluid from a suitable reservoir shown schematically as 154 anddischarges it through a flow divider valve 158, which in turn directsthe fluid through two separate lines according to the priority of theflow divider valve to a valve block assembly 160. All of these units arepreferably and conveniently secured to the tubular section 12 of thesupport frame 10 between the front and rear support sections 13 and 14so that they are easily accessible when the machine is in operation sothat the operator can observe the cutting action, while the controls andthe operator are in a relatively safe position spaced back from thecutting head.

The valve block 160 consists of a number of opencenter hydraulic valvesmounted in a stacked arrangement and connected to each other to have acommon drain and supplied with fluid pressure by inlet sections.

The discharge from the flow divider valve 158 passes through twoseparate lines to the valve block 160, with the line 161 having a smallpriority flow being connected to an inlet section 162 of the valveblock. From the inlet section 162, fluid is supplied to the adjacentpair of lift cylinder valves 163 which are connected by lines 164 and165 to the lift cylinders 142 to provide for reversible actuation. Aspreviously stated, the valves 163 are opencenter valves so that if theyare not in operation, which is the case except when the support frame isbeing positioned forwardly in preparation for another cutting cycle,substantially all of the fluid entering the inlet section 162 passesthrough to drain through the remaining units of the valve block.

The next unit in the valve bank is a second inlet section 167 which issupplied with fluid through line 168 in the manner describedhereinafter. Inlet section 167 supplies fluid to a push cylinder controlvalve 171 connected through lines 172 and 173 to all of the pushcylinders 135. It should be noted that all of these cylinders areconnected in parallel so that they will operate as a unit at the samepressure so as to insure an even pushing action on the cutter head.

The next unit in the valve bank is a third inlet section 175 which issupplied with fluid through line 176 having the larger amount of flowfrom the flow divider valve 158. This third inlet section 175 suppliesthe fluid to a selector valve 178 which is utilized for selectivecontrol of the fluid supply for actuation of the holding cylinders in amanner to be described in greater detail hereinafter. The drain flowfrom the open-center valves 171 and 178 passes into a drain section 179to return excess fluid back to the reservoir 154.

The selector valve 178 is operable in two directions to connect the flowfrom the inlet section 175 into either line 181 or line 188. Line 181 isconnected to a flow divider valve 182 which has a low volume priorityflow outlet connected through a check valve 183 to a line 184 whichserves as the supply to the valves for the holding cylinders. The otheroutlet from flow divider valve 182 of lower priority but higher rate offlow is connected through line 186 to line 168 which supplies the fluidto the second inlet section 167. An adjustable relief valve 170 isconnected to the line 168 so that the pressure level of the fluidsupplied to the inlet section 167 may be easily regulated by theoperator. Since the flow from inlet section 167 goes to the pushcylinders 135, the relief valve 170 thereby serves as a convenientadjustment for the pressure in the push cylinders 135 and therefore as ameans of regulating the axial force applied to the cutter head. Therelief valve 170 is therefore operated in a manner that the cuttingpressure may be maintained at the level giving the highest degree ofcutting efficiency without danger of overloading the electric cutterdrive motors 89, which could occur if too much pressure is applied tothe cutter head. It will be seen that fluid is supplied to the inletsection 167 only when the selector valve 178 is in a position todischarge the fluid from the third inlet section 175 through line 181 tothe flow divider valve 182. Under these conditions, only a small flowrate passes through the check valve 183 to the line 184 to provide amake-up fluid supply to the holding cylinders 21 so that these holdingcylinders are pressurized at all times while cutting takes place.

When the selector valve 178 is shifted to the opposite position todischarge the fluid received from inlet section 175 into line 188, allof the fluid from the inlet section 175 is available to pass through thecheck valve 189 back to the line 184 to be available for actuation ofthe holding cylinders. Accordingly, line 184 is connected to the bank ofeight holding cylinder control valves 191 for selective actuation of theholding cylinders 21 to which they are connected by lines indicated at192 and 193. There is one valve for each holding cylinder connected inits own circuit to allow separate and independent actuation of theholding cylinders, and since these are open-center valves, theconnection of the line 184 to one of the valves provides a supply forall of them. The holding cylinder control valves 191 are at the end ofthe valve block 160 opposite the drain section 179, and any excess flowwhich reaches the last holding cylinder control valve indicated at 194then passes to drain through the drain passages through the remainder ofthe valve bank until it reaches the drain section 179 where it isreturned to the reservoir as indicated at 154.

Turning now to the operation of the circuit, it will be assumed that themachine has finished a cutting cycle and the support frame has beenmoved to a forward position, that is with the carriage frame in aretracted position and the holding cylinders 21 are retracted. Since thepush cylinders will then be inoperative and the lift cylinders locked,all of the valves in the system will then be in a neutral position. Thenext step is to expand the holding cylinders, and since these cylinders,because of the large forces they must exert, are of large diameter andstroke compared to the capacity of the pump, maximum flow is needed forthe initial rapid movement to bring them into contact with the tunnelwall. In this case, the selector valve 178 is actuated to direct thefluid into the line 188 so that the full flow from flow divider valve158 through line 176 will flow past the check valve 189 into the line184 so that actuation of the holding cylinder valves 191 will move thecylinders at a maximum speed to allow the holding pads to reengage thetunnel wall. After they have been moved into engagement or close toengagement, the selector valve 178 will be shifted to the other positionwhere it will remain during the cutting cycle. This allows the fluid t0flow into the line 181 to the flow divider 182 so that a small flow atall times will be provided into the line 184. This flow, because of thelow volume, allows the holding cylinders to be actuated at a lower ratefor precise positioning of the support frame, after which all of theholding valves 191 remain in the operating position to maintain thepressure in the holding cylinders during the cutting action, and thissmall flow will then be more than sufiicient to overcome any leakage inthe system.

After the sup-port frame has thus been positioned, the lift cylindervalves 163 will then be actuated to retract the lift cylinders afterwhich the valves will return to the neutral position. When this is done,the push cylinder valve 171 will be actuated to direct the fluid flowthrough the push cylinders to start the cutting action. Of course, thecontrol of the electric motors is independent of the hydraulic systemand these will be started before the push cylinders are actuated andstopped when the retraction portion of the cycle is started. Thus, theflow divider 182 operates together with the selector valve 178 and thecheck valves 183 and 189 to allow a selective large and small volume forthe holding cylinders. The other flow divider valve 158 operates toallow only a small flow through the lift cylinder section so that mostof the pump output flow is available at the third inlet section 175.

When the cutting cycle is completed, the drive motors will be turned offand the push cylinder valve 171 returned to the neutral position. Thelift cylinder valve 163 will then be actuated to extend the liftcylinders 142 after which the holding cylinders will be retracted. Toallow for high speed retraction, the selector valve 178 is thus reversedto the position to direct the flow into the line 188 for fastretraction. After this is done, the selector valve 178 is again reversedto supply fluid to the second inlet section 167 and the push cylindervalve 171 is actuated to reverse the action of these cylinders and thenshift the support frame in a forwardly direction. Selector valve 178 isthen moved to direct fluid into line 188 for best operation of theholding cylinder 21.

Because the torque arms are required both to support the load of thecarriage structure, transmit the reaction torque to the support frameand resist shock loading both from impact and from torque fluctuations,it is important that the pivot connection between the two parts of thetorque arm be able to absorb resilient shock loads in a directionopposite to the normal torque transmitting direction. An alternativeconstruction for the torque arm pivot pin is shown in FIGURE 8. Thetorque arms are generally constructed the same as torque arms 97 and 107and have projecting ears 201 and 202. Within the ears 201 and 202 aresuitable bushings 204 and 205 which rotatably and slidably journal apivot pin 207. The torque arms 201 and 202 are spaced apart by a pair ofhardened thrust washer bearings 208 which are non-rotatably positionedon the torque :arms by locating pins 209. Immediately outward of thetorque arms are a pair of roller thrust bearings 211, one on each sideand positioned around the pivot pin 207. Outward of each of the rollerbearings 211 is a resilient thrust washer assembly including an innerwasher 213 and :an outer Washer 214 of a suitable rigid material such assteel. The washers 213 and 214 are spaced apart axially and spacedradially from the surface of the pivot pin 207 by an elastomericmaterial indicated at 215. This material is preferably a polyurethaneresin and may be f the same type as that used for the mounting of thecutter assembly. The outer ends of the pivot pin 207 are threaded toreceive nuts 218 which serve to provide a loading on thethrusteabsorbing Washer assemblies and the bearings as well as to absorbthe reverse thrust forces when the torque arms are urged apart. In orderto lock the nuts 218 securely in position on the pivot pin, the nutshave a slot 219 extending parallel to their faces and substantiallyhalfway through the nuts. A lockscrew 221 is threadedly engaged on oneside of the slot with its head on the other slot so that by tighteningthe edges of the slot 219 are brought together. By this action, theinternal threads on the nut are distorted in the manner to firmly clampthe nut in position. With this arrangement, the normal driving forcesare taken up through the hardened thrust Washers 208 in the same manneras in the torque arm pivot pin arrangement shown in FIGURE 7. However,when reverse forces tend to separate the torque arms, both arms willtend to slide along the pivot pin to compress the elastomeric material215 and allow resilient absorption of the shock loads.

As previously pointed out, because the reaction force of the drive forthe cutter assembly takes place at the drive housing 79, the rear torquearm assemblies are primarily responsible for transmitting the torque tothe support frame and the front torque arm assemblies connected to thefront support section 13 are used principally to position the carriageframe tube 26 and to absorb radial and tangential impact loads from thecutter head. Therefore, it is possible to substitute a suitable bearingfor the front torque arm assemblies if the hearing will be able toabsorb these radial and tangential loads, thereby leaving to the reartorque arm assembly the transmission of the driving torque between thedrive housing and the support frame.

An alternative arrangement of this type is shown in FIGURE 9 where thefront support section 225, generally corresponding in structure to thefront support section 13, is provided at its forward end with an annularrecess within which is fitted an outer sleeve 229 secured in place bybolts 230. The carriage frame tube 232 has a cylindrical section at thispoint which is slidably journalled within a suitable bearing 233 toallow the longitudinal reciprocation of the tube 232. The bearing 233 isspaced radially from the sleeve 229 by a layer of elastomeric material234 which may be of a polyurethane elastomer mentioned herein above.With this arrangement, the bearing 233 is positively positioned withrespect to the tube 232 against radial movement, while the bearing isgiven limited radial movement by the el-astomeric material 234 in orderto absorb such shock loads. To provide a seal around the bearing 233 toprevent the entrance of rock dust. and other material which wouldquickly damage the barrel, a tubular bellows 236 is clamped at 238 tothe outer sleeve 229 and at its other end clamped at 239' to the rearface of the cutter head housing 240.

While the invention has been shown and described in detail hereinabove,it is recognized that various modifications and rearrangements willoccur to those skilled in the art upon a full comprehension of thisinvention, and such modifications and rearrangements may be resorted towithout departing from the scope of the invention as defined in theclaims.

What is claimed is:

1. A tunnel excavating machine comprising a support frame, a movableframe carried by said support frame and having cutting means thereon,pushing means including an expansible chamber fluid motor for providingrelative movement between said support frame and said movable frame toforce said cutting means into engagement with the face of the tunnelbeing cut, holding means for said support frame including an expansiblechamber fluid motor adapted to grip the tunnel walls, a source of fluidpressure, a control valve for said holding motor, a control valve forsaid push motor, a selector valve having .an inlet connected to saidfluid pressure source and first and second outlets, said first outletbeing connected to said holding control valve, a flow dividing valvehaving an inlet connected to said second outlet, said flow divider valvehaving a reduced priority flow outlet connected to said holding controlvalve and a high flow outlet connected to said push control valve,whereby selective operation of said selector valve connecting said inletto said first outlet provides full flow from said fluid pressure sourceto said holding control valve for maximum speed of operation andoperation of said selector valve to connect said inlet to said secondoutlet provides a reduced priority flow to said holding control valveand a high flow to said push control valve.

2. A tunnel excavating machine as set forth in claim 1 wherein saidcontrol valves and said selector valve are of the open-center type, andincluding a first check valve connected to said selector valve firstoutlet and a second check valve connected to said flow divider valvereduced priority flow outlet.

References Cited UNITED STATES PATENTS ERNEST R. PURSER, PrimaryExaminer.

